Flavonoids from artocarpus Scortechinii King

Abstract

Artocarpus scortechinii King locally known as 'terap hitam' is classified under the family of Moraceae. Phytochemical study on this species had been carried out using cold extraction method with increasing polarity of solvent i.e. n-hexane, dichloromethane, ethyl acetate and methanol. The plant sample was collected from Bukit Fraser, Pahang. Two parts of the plant which were stem barks and leaves had been investigated. Total of six known compounds were isolated from stem barks part and identified as 4',5-dihydroxy-6,7-(2,2dimethylpyrano)- 2'-methoxy-8-y,y-dimethylallyflavone (1), artocarpin (2), artonin E (3) , oxyresveratrol (4), cudraflavone A (5) , cycloartobiloxanthone (6). Another compound identified as flemmichapparin A (7) obtained from leaves of A. scortechinii. The structures were elucidated spectroscopically using 10 NMR ('H, 13C, DEPT), 20 (COSY, HMQC, HMBC), UV, MS and FTIR. All crude extracts and seven isolated compounds were tested for their total phenolic content (TPC) and ant ioxidant activities using ferric reducing antioxidant potential (FRAP) and 2,2'-azinobis(3-ethyl-benzothiazoline-6-sulfonic acid) (ABTS) assays. Among all crude extract tested, the methanol extract of the stem barks showed the highest phenolic content with the TPC value of 136.84 mg GAE/g dw and followed by ethyl acetate and dichloromethane extracts of the stem barks with TPC value of 105.56 and 73.93 mg GAE/g dw respectively. Ethyl acetate extract of the stem barks showed the most significant reducing potential ranges between 0.27-2.47 mM FRAP equivalent. Cycloartobiloxanthone (6) showed the most potent ferric ion reducer among all isolated compounds with reducing potential ranging from 0.60 to 2.79 mM FRAP equivalent. For the ABTS assay, the cavenging activity for the ethyl acetate extract of the stem barks was the highest with cavenging percentage of 90.9% which is slightly higher than methanol extract of the stem barks (90 .6%) at the concentration of 1.0 mM. As for the isolated compounds, oxyresveratrol (4) acted as the most potent scavenger with scavenging percentage of 91.2%. Butylated hydroxyanisole (BI-IA), butylated hydroxytoluene (BHT) and 6-h ydroxy-2,5,7,8 tetramethylchroman- 2-carboxylic acid (Trolox) were used as the standard control.